This invention relates to automated data storage libraries, and, more particularly, to libraries having a plurality of pickers for accessing data storage media stored in the library, and for accessing and delivering the media between media storage slots and read/write stations.
Automated data storage libraries are known for providing cost effective access to large quantities of stored data. Generally, data storage libraries include a large number of media storage slots on which are stored portable data storage media. The typical data storage media is a tape cartridge or an optical disk cartridge. A picker typically accesses the data storage media from the media storage slots and delivers the accessed media to a data storage drive at a read/write station for reading and/or writing data on the accessed media. The operation of the picker is under the control of a library controller which is coupled by wires to suitable electronics, such as an accessor or robot control, which operates servo motors to move the picker.
The need to store ever increasing numbers of volumes of data with the ability to access that data rapidly has led to the use of high capacity automated data storage libraries with multiple pickers.
Conventional automated data storage libraries having multiple pickers avoid collisions by assigning pickers to zones within the library. An example is U.S. Pat. No. 5,513,156. These zones are separated by a zone boundary area which prevent two pickers from interfering with each other. When a media is to be moved to an area outside of the normal zone of a picker, either the media is exchanged from a first picker to a second picker by delivering it to a storage slot accessible by both pickers, or the zone boundary is moved, or the second picker is moved out of the way or into a garage.
Thus, the read/write stations must be positioned at different locations in the library so that they can be separately accessed by each of the pickers in its zone. Further, if all of the data storage media requested by the host system is in one zone of the library, all of the media must be accessed by a single one of the pickers, while the other picker is idle. Still further, if a read/write station in one zone is inoperative, the picker for that zone has only reduced capability because it has no access to the other read/write stations in the other zone. As the result, the effectiveness of the library is reduced.
Additionally, the conventional library controller directly controls the operation of the pickers, and is coupled to the pickers by means of electrical wiring to operate the robot servo processor in each picker. Thus, the library is subject to failure of the wiring between the controller and the multiple pickers, and the pickers must be operated so that the wiring does not become tangled. A library having storage cells below a floor laying in a horizontal plane with wireless vehicles for accessing the storage cells is shown in coassigned U.S. Pat. No. 5,395,199, but employs a single central control processor to operate the vehicles and does not consider possible interference between the vehicles.
Thus, the above libraries are vulnerable to the failure of the library controller or to the failure of one of the pickers, and the library effectiveness is reduced by the need to adjust the operation of the pickers because of the presence of the zones, and further reduced by the need to sense the situations requiring adjustment of the zones.
An object of the present invention is to increase the effectiveness of a library having multiple pickers.
Disclosed is a wireless communication link providing picker to picker communication between multiple intelligent pickers for an automated data storage library, and providing central communication between at least one of the pickers with a central job queue.
A library controller receives input commands for jobs to move media amongst media storage slots and read/write stations, the library controller identifying the received move jobs, and placing the move jobs in a central job queue.
Each intelligent picker comprises at least one gripper for accessing and delivering media at the media storage slots and the read/write stations, and a processor for operating the picker to conduct a move job and providing movement information describing movement of the picker for the current move job of the picker.
The wireless communication link comprises a wireless central communication link between at least one of the pickers and the central job queue for communicating a move job to the picker processor from the central job queue, and a wireless picker to picker communication link, coupled to the picker processor of at least two of the pickers, for communicating between the pickers, each linked picker transmitting the movement information over the wireless picker to picker communication link.
In one embodiment, the wireless picker to picker communication link comprises infrared transceivers at each linked picker coupled to the picker processor. The wireless central communication link comprises the infrared transceiver at one of the pickers and an infrared transceiver at the central job queue, coupled to the central job queue. Additionally, the wireless central communication link may be coupled to the library controller, whereby the linked picker processor additionally periodically communicates with the library controller over the wireless central communication link, the library controller additionally determines whether the periodic communication has been received from each of the linked pickers within a predetermined time period, and the library controller additionally, upon failing to receive the periodic communication from each the picker within the predetermined time period, indicates an error.
For a fuller understanding of the present invention, reference should be made to the following detailed description taken in conjunction with the accompanying drawings.